I am on KDE4.3.4 and both FF and TB take between 50 seconds and 1 minute to load. Is this sort of average loading time? I find it far too long.
I was getting similar with FFox and OOo and I found this suggested in another thread (cant find it at the mo, but noted the instructions down)
Open synaptic package manager and search for package gtk-qt-engine, kde4-style-qtcurve, qtcurve-gtk2.
Mark them for installation (oxygen-molecule will be removed with it)
Open KMenu > System > Configuration > Configure Your Desktop
Find and Click Look and Feel > Appearance > Gtk Themes and Fonts
in GTK Styles choose Use another style and pick QtCurve
in GTK Fonts choose Use KDE fonts in my GTK applications
Click Install scrollbar fix below
Reboot or restart X server.
This worked for me - all apps open fast as expected